The invention herein is related to landing gears for semi-trailers and the like. Commonly, such landing gears are formed with interfitting box-section supporting legs, as shown for example, in the U.S. patent of Lozada et al, U.S. Pat. No. 4,124,225 issued Nov. 7, 1978 and assigned to the same assignee as this invention. Commonly, such landing gears must withstand, in testing, a 70,000 pound static load without collapsing or failure. Further, a pair of such landing gears must commonly be capable of lifting a 50,000 pound load. Landing gears made with conventional box-section legs as shown in U.S. Pat. No. 4,124,225 have commonly had legs formed of square tubing with a thickness of 0.185", in order to provide the necessary strength.
Another landing gear leg which has been successfully used is the corrugated oval form as shown in the U.S. Pat. No. Des. 190,564 of Homan, issued June 13, 1961. In that construction, the inner and outer legs are formed of a generally oval corrugated design, but with non-interfitting corrugations. This construction is lightweight and strong, but is expensive to manufacture. The corrugations are not arranged in complementary fashion or otherwise interfit or cooperate to increase strength and rigidity.